package store

import (
	"context"
	"database/sql"
	"errors"
	"fmt"
	"time"
)

// NotificationChannel mirrors a row in notification_channels. The
// Config field is the AEAD-encrypted JSON blob; callers (in the
// notification package) decrypt before use.
type NotificationChannel struct {
	ID              string
	Kind            string // "webhook" | "ntfy" | "smtp"
	Name            string
	Enabled         bool
	Config          []byte // AEAD ciphertext; opaque at this layer
	DefaultPriority *string
	CreatedAt       time.Time
	UpdatedAt       time.Time
	LastFiredAt     *time.Time
}

// NotificationLogEntry is one row in notification_log.
type NotificationLogEntry struct {
	ID         string
	ChannelID  string
	AlertID    *string
	Event      string // alert.raised | alert.acknowledged | alert.resolved | alert.test
	OK         bool
	StatusCode *int
	LatencyMS  *int
	Error      *string
	FiredAt    time.Time
}

// CreateNotificationChannel inserts a new notification channel row.
func (s *Store) CreateNotificationChannel(ctx context.Context, ch NotificationChannel) error {
	enabled := 0
	if ch.Enabled {
		enabled = 1
	}
	_, err := s.db.ExecContext(ctx,
		`INSERT INTO notification_channels
		   (id, kind, name, enabled, config, default_priority, created_at, updated_at)
		 VALUES (?, ?, ?, ?, ?, ?, ?, ?)`,
		ch.ID, ch.Kind, ch.Name, enabled, ch.Config,
		nullable(ch.DefaultPriority),
		ch.CreatedAt.UTC().Format(time.RFC3339Nano),
		ch.UpdatedAt.UTC().Format(time.RFC3339Nano))
	if err != nil {
		return fmt.Errorf("store: create channel: %w", err)
	}
	return nil
}

// UpdateNotificationChannel updates mutable fields on an existing channel row.
func (s *Store) UpdateNotificationChannel(ctx context.Context, ch NotificationChannel) error {
	enabled := 0
	if ch.Enabled {
		enabled = 1
	}
	_, err := s.db.ExecContext(ctx,
		`UPDATE notification_channels
		   SET kind = ?, name = ?, enabled = ?, config = ?,
		       default_priority = ?, updated_at = ?
		 WHERE id = ?`,
		ch.Kind, ch.Name, enabled, ch.Config,
		nullable(ch.DefaultPriority),
		ch.UpdatedAt.UTC().Format(time.RFC3339Nano),
		ch.ID)
	if err != nil {
		return fmt.Errorf("store: update channel: %w", err)
	}
	return nil
}

// DeleteNotificationChannel removes a channel row; cascades to notification_log.
func (s *Store) DeleteNotificationChannel(ctx context.Context, id string) error {
	_, err := s.db.ExecContext(ctx,
		`DELETE FROM notification_channels WHERE id = ?`, id)
	if err != nil {
		return fmt.Errorf("store: delete channel: %w", err)
	}
	return nil
}

// GetNotificationChannel returns one channel by primary key or ErrNotFound.
func (s *Store) GetNotificationChannel(ctx context.Context, id string) (*NotificationChannel, error) {
	row := s.db.QueryRowContext(ctx,
		`SELECT id, kind, name, enabled, config, default_priority,
		        created_at, updated_at, last_fired_at
		   FROM notification_channels WHERE id = ?`, id)
	return scanChannel(row.Scan)
}

// ListNotificationChannels returns all channels ordered by created_at ascending.
func (s *Store) ListNotificationChannels(ctx context.Context) ([]NotificationChannel, error) {
	rows, err := s.db.QueryContext(ctx,
		`SELECT id, kind, name, enabled, config, default_priority,
		        created_at, updated_at, last_fired_at
		   FROM notification_channels ORDER BY created_at ASC`)
	if err != nil {
		return nil, fmt.Errorf("store: list channels: %w", err)
	}
	defer func() { _ = rows.Close() }()
	var out []NotificationChannel
	for rows.Next() {
		c, err := scanChannel(rows.Scan)
		if err != nil {
			return nil, err
		}
		out = append(out, *c)
	}
	return out, rows.Err()
}

// ListEnabledNotificationChannels returns only channels with enabled=1, ordered by created_at.
func (s *Store) ListEnabledNotificationChannels(ctx context.Context) ([]NotificationChannel, error) {
	rows, err := s.db.QueryContext(ctx,
		`SELECT id, kind, name, enabled, config, default_priority,
		        created_at, updated_at, last_fired_at
		   FROM notification_channels WHERE enabled = 1 ORDER BY created_at ASC`)
	if err != nil {
		return nil, fmt.Errorf("store: list enabled: %w", err)
	}
	defer func() { _ = rows.Close() }()
	var out []NotificationChannel
	for rows.Next() {
		c, err := scanChannel(rows.Scan)
		if err != nil {
			return nil, err
		}
		out = append(out, *c)
	}
	return out, rows.Err()
}

// AppendNotificationLog records a delivery attempt + bumps the
// channel's last_fired_at on success.
func (s *Store) AppendNotificationLog(ctx context.Context, e NotificationLogEntry) error {
	tx, err := s.db.BeginTx(ctx, nil)
	if err != nil {
		return fmt.Errorf("store: begin: %w", err)
	}
	defer func() { _ = tx.Rollback() }()

	ok := 0
	if e.OK {
		ok = 1
	}
	_, err = tx.ExecContext(ctx,
		`INSERT INTO notification_log
		  (id, channel_id, alert_id, event, ok, status_code, latency_ms, error, fired_at)
		 VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)`,
		e.ID, e.ChannelID, nullable(e.AlertID), e.Event, ok,
		nullableInt(e.StatusCode), nullableInt(e.LatencyMS),
		nullable(e.Error),
		e.FiredAt.UTC().Format(time.RFC3339Nano))
	if err != nil {
		return fmt.Errorf("store: append notification_log: %w", err)
	}

	if e.OK {
		if _, err := tx.ExecContext(ctx,
			`UPDATE notification_channels SET last_fired_at = ? WHERE id = ?`,
			e.FiredAt.UTC().Format(time.RFC3339Nano), e.ChannelID); err != nil {
			return fmt.Errorf("store: bump last_fired_at: %w", err)
		}
	}
	return tx.Commit()
}

func scanChannel(scan func(...any) error) (*NotificationChannel, error) {
	var c NotificationChannel
	var enabled int
	var defaultPri, lastFired sql.NullString
	var createdAt, updatedAt string
	if err := scan(&c.ID, &c.Kind, &c.Name, &enabled, &c.Config,
		&defaultPri, &createdAt, &updatedAt, &lastFired); err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return nil, ErrNotFound
		}
		return nil, fmt.Errorf("store: scan channel: %w", err)
	}
	c.Enabled = enabled == 1
	if defaultPri.Valid {
		v := defaultPri.String
		c.DefaultPriority = &v
	}
	t, err := time.Parse(time.RFC3339Nano, createdAt)
	if err != nil {
		return nil, fmt.Errorf("store: parse created_at: %w", err)
	}
	c.CreatedAt = t
	t, err = time.Parse(time.RFC3339Nano, updatedAt)
	if err != nil {
		return nil, fmt.Errorf("store: parse updated_at: %w", err)
	}
	c.UpdatedAt = t
	if lastFired.Valid {
		t, _ := time.Parse(time.RFC3339Nano, lastFired.String)
		c.LastFiredAt = &t
	}
	return &c, nil
}